One of the main ways that CCP fights companies engaging in selling isk in Eve Online is through the sale of PLEX. PLEX, or Pilot's License EXtention, is good for paying for 30 days of subscription for the game. The item can be traded on the market for isk, thus not only allowing people to purchase isk for cash legally, but also allowing other players to basically pay their subscriptions with in-game currency. A nice solution to an ugly problem.
But would I ever take advantage of purchasing isk with real life money? I can't see myself doing that. Why? Not for moral reasons, since buying isk is sanctioned by CCP. Instead, I wouldn't buy isk because of the way I play games. When I play games, I always find the journey more enjoyable than what I find at the end. In Eve, a major part of the journey is making the isk to do all the things I want to do. So for me, buying isk is the equivalent of the offline leveling offered in Age of Conan.
Let me give a current example. One of my current goals is to purchase and fly an Orca. Now, I could just go ahead and purchase 2 PLEX for $34.99 and then have enough isk to buy an Orca and have enough to spare to fit it out properly. Or, I could figure out how to pay for one using completely in-game play. Right now my quest for an Orca has led me into planetary interaction and gearing up to do level 4 missions. As part of doing missions, I started investigating invention in order to produce tech 2 drones. And once I figure out making drones, I will have the knowledge to make larger items like Cheetahs and Prowlers.
Some players don't want to go through all the time and effort to get their ship. For them, paying $35 gets them past all the work and they can do what they really want to do. But for me, overcoming all the obstacles and learning more about New Eden is much more satisfying. And since Eve is a sandbox, I'll play the way I want to.